This invention relates to novel polymer-organoclay composite compositions. More particularly, the instant invention relates to composite materials containing both organoclays and organic polymers bearing amine groups. The organoclays described by the instant invention are those that incorporate a secondary, tertiary or quaternary ammonium ion. Additional optional components of these composite materials are a second thermoplastic polymer, an impact modifying agent and a compatibilizing agent.
Materials in which an organoclay is highly and uniformly dispersed in a polymer matrix are prized for their greater resistance to the effects of heat compared to systems containing a clay component which is less highly dispersed. Resistance to heat induced deformation of a molded part prepared from polymeric materials is critical in applications where the part is to be painted and then subjected to a high heat baking step as is frequently the case in the automotive industry. Polymer-organoclay composite compositions, sometimes referred to as nanocomposites, having improved heat resistance have been prepared by combining a variety of materials including polyamides and polyphenylene ethers with organoclays, impact improving additives and compatibilizing agents. Although addition of an organoclay improves the heat resistance of a material, the presence of the organoclay may result in loss of molecular weight of one or more of the polymer components of the composition during extruding and molding steps. The effect of this loss of molecular weight of one or more of the polymer components has the effect that articles molded from the composition are less robust than they would be absent the loss of molecular weight. In other instances the organoclay may not exfoliate and disperse uniformly within the polymer matrix. In such cases the compositions do not exhibit the enhanced physical properties of nanocomposites where the physical properties of the composition are closely tied to the size and uniformity of dispersion of the organoclay particles. There is a continuing need to improve the overall performance characteristics of polymer-organoclay composite compositions as a function of the size of the organoclay particles, which is dependent upon the extent to which the organoclay particles exfoliate, the uniformity of dispersion of the organoclay particles within the composition and the chemical stability of the constituent polymers. Particularly, there is demand for improved performance characteristics among polymer-organoclay composite compositions comprising both polyamides and polyphenylene ethers. The instant invention is based on the discovery that certain organoclays may be employed as components of polymer-organoclay composite compositions which are not subject to these limitations.
The present invention overcomes earlier limitations on the use of organoclays in polymer-organoclay composite compositions by adjustment of the structure of the ammonium ion in the organoclay component. These and further objects of the invention will be more readily appreciated when considering the following disclosure and appended claims.
In one aspect, the invention relates to polymer-organoclay composite compositions comprising:
(A) at least one organic thermoplastic polymer bearing amine groups;
(B) at least one organoclay comprising organic ammonium cations having structure I 
xe2x80x83wherein each R1, R2, R3 and R4 is independently a hydrogen, C1-C18 alkyl group or a C3-C18 cycloalkyl group, wherein no more than two of the groups R1, R2, R3 and R4 are hydrogen; and wherein no more than one of the groups R1, R2, R3 and R4 is an alkyl group or cycloalkyl group having more than 10 carbon atoms;
or in the alternative having structure II 
xe2x80x83wherein R5 is a C1-C18 alkyl group and R6, R7 and R8 are hydrogen atoms or methyl groups wherein at least one of R6, R7 and R8 is a methyl group;
said organoclay being present in an amount in a range between about 0.1 weight percent and about 40 weight percent, based on the total weight of components (A), (B), (C), (D) and (E);
(C) a thermoplastic resin different from component (A), said thermoplastic resin being present in an amount in a range between about 0.0 weight percent and about 90 weight percent, based on the combined total weight of components (A), (B), (C), (D) and (E);
(D) an impact modifying agent, said impact modifying agent being present in an amount in a range between about 0 weight percent and about 20 weight percent, based on the combined total weight of components (A), (B), (C), (D) and (E); and
(E) a compatibilizing agent in an amount in a range between about 0 weight percent and about 10 weight percent, based on the total weight of components (A), (B), (C), (D) and (E).
The invention further relates to methods of making these compositions and molded articles prepared from them.